But with great fans, comes great responsibility. So the show had to be very careful when, after five years of will-they-or-won't-they tension, Psych kicked off its sixth season with Shawn (Roday) and Juliet (Maggie Lawson) as a full-fledged couple. It's been a long time coming, but Roday is all too familiar with the TV graveyard filled with shows that died after their lead characters coupled up.

"You're always worried you're going to jump the shark with stuff like this because there are so many other shows that failed in the attempt to put two characters together," Roday says. "It's been an interesting process to make sure we service this new relationship and let people feel like, 'Alright, they are in a relationship and they are evolving,' but also making sure that Shawn and Gus are still the center of the Psych universe.

"To our credit and to the credit of our writing staff, I think we did a pretty nice job of not mixing things up too much," Roday continues. "The truth is the basis of Shawn and Juliet's relationship is their work. That's how they met, that's what they do the most. So in that sense, they've always been kind of a team and not a lot changes there. ... I think the fans will be pleased that we're serving the relationship, but not at the expense of any of the other stuff that they've come to love and expect."

However, putting Shawn and Juliet together will still come at a cost to Gus (Dulé Hill). Now that he has to share his long-time partner-in-crime with Juliet, Gus will have more time to dwell on his own personal relationships. Or, more accurately, the lack thereof. "It affects him in a pretty dramatic way. He just panics, and his mojo and his drive for companionship goes into overload," Roday says. "He's not even sure of what he wants; he just knows he wants something. It's basically him saying, 'Wait a minute, I don't want to be the guy that's left without a chair when the music stops.'"

Check out Hill had to say about his on-screen partner's new relationship:

Gus' sudden bout with loneliness comes just as he and Shawn will begin to become more aware of their own mortality. "Like all men, there comes a point where you have to acknowledge that, 'OK, we're not that young anymore. We still feel young, but it's getting harder to chase people and you go down after one punch instead of two or three,'" Roday says. "Most of it is great for comic effect: there's a lot of pulled hammies, black eyes. ... It's just the two of them coming to grips with the fact that it's only going to get harder... but it's still worth it to them."

Shawn and Gus may be feeling growing pains on-screen, but the series is showing no such signs of aging. The Season 6 premiere was up eight percent from last fall's premiere (2.99 million viewers) and the mystery-comedy is now USA's longest-running show on the air. "We had a great, great way in because of Tony Shalhoub and what he did with Monk, but we were able to kind of do the same thing and reach a younger audience. We kind of carved out our own little niche," Roday says. "We were able to come on and find our own success. Monk only lasted a little while longer and there we were as the lone quirky comedy on USA."

Five years later, Psych is just one in an army of light, character-driven procedurals at USA (see: Burn Notice, Royal Pains). Even so, Shawn and Gus have managed to stand apart from the Michael Westens and Dr. Hanks thanks to its unique, irreverent humor and pop culture-savy scripts. (This season's homage episodes include Raiders of the Lost Ark, Clue and The Bachelorette.)

"We've managed to create a universe where there is hardly anything that we can't get away with and still call it Psych," Roday says. "There are almost no rules as long as we solve a murder every week. I think we take full advantage of that. ... At some point, we just started evolving into this show that just does whatever it wants, and I think that's when we really put our stamp on what we're doing creatively."